<!--
 * @Author: your name
 * @Date: 2022-02-21 18:31:16
 * @LastEditTime: 2022-02-21 18:40:49
 * @LastEditors: Please set LastEditors
 * @Description: 打开koroFileHeader查看配置 进行设置: https://github.com/OBKoro1/koro1FileHeader/wiki/%E9%85%8D%E7%BD%AE
 * @FilePath: \gitCK\day-4\circle.html
-->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>嵌套圆</title>
    <style>
        .outer , .inner{
            box-sizing: border-box;/* width:padding+border+内容*/
            border-radius: 50%;
        }
    .outer{
        width: 300px;
        height: 300px;
        border: 3px solid #ccc;
        margin: 0 auto;
        padding: 50px;
        transition: padding 2s;
    }
    .outer:hover{
        padding: 10px;
    }
    .outer .inner{
        width: 100%;
        height: 100%;
        border: 5px solid #ccc;

    }
    </style>
</head>
<body>
    <div class="outer">
        <div class="inner">

        </div>
    </div>
</body>
</html>